Abstract: Modified activated carbon Fe-K/AC (activated carbon supported iron and potassium) was used as an oxidation catalyst for low concentration hydrogen sulfide (H₂S) removed. The orthogonal design method was introduced in the research of Fe-K/AC preparation to determine the optimum condition and to measure the impact of different factors. Then, catalytic activity and mechanism on Fe-K/AC catalyst for oxidation of hydrogen sulfide was investigated. The optimum preparation condition of Fe-K/AC with high sulfur capacity and selectivity is that the iron and potassium content is 0.5% and 5.0%, respectively; and the calcination temperature and the Fe²⁺/Fe³⁺ atomic ratio is 600 ℃ and 0.5, respectively. The order of their influences is potassium content > iron content > calcination temperature > Fe²⁺/Fe³⁺ atomic ratio. Results from structural parameters and surface morphology of sorbents reveal that iron metal oxide loaded on the surface of activated carbon has the selective catalytic oxidation activity of hydrogen sulfide to element sulfur. Alkali metal oxide, which changes basic surface groups, has a synergistic effect on the catalytic oxidation of hydrogen sulfide. However,the catalytic activity decreases due to excessive metal oxides loadings that may block the accessibility of micropores and reduce the surface area.